This invention relates generally to cellulosic animal litters and, more particularly, to clumping cellulosic animal litters made from specially treated agglomerated cellulosic particles.
Small domesticated animals, such as cats, are often trained to urinate and defecate in special containers commonly referred to as litter boxes. Untrained caged animals, such as guinea pigs, hamsters, gerbils, dogs, birds, monkeys, ferrets and laboratory mice and rats urinate and defecate on the floors of their cages. Therefore, pet owners, veterinarians and laboratory personnel line the bottoms of litter boxes and cages with absorbent material to collect the animals' urine and feces. In order to control objectionable odors from the contaminated absorbent material, it is necessary to periodically remove and dispose of that material and to replace it with fresh absorbent material.
Until recently, it was found to be necessary to completely remove contaminated absorbent material from the litter boxes and cages. However, now clay-based absorbents materials have been developed which, when wetted with animal urine, form coherent clumps that may be easily segregated and removed from the remaining uncontaminated absorbent material. These clay-based absorbents, which are generally referred to as "clumping litters", are far more efficient and convenient to use than prior absorbent materials. As a result, they have gained widespread commercial acceptance.
Unfortunately, clay-based absorbents have some drawbacks. First, they are dusty. Second, they are relatively expensive since they require that the clay be mined, processed, and often shipped long distances. The mining process is not only expensive, it can scar the landscape and is therefore environmentally undesirable. Also, different types of clay must be combined and treated in certain ways in order to achieve the desired clumping effect.
Substrates containing at least 10% by weight cellulosic content are a known alternative to clay-based absorbents for use in absorbing and disposing of animal urine and feces. When such cellulosic materials are made from waste produced in paper manufacture, they offer significant advantages over clay-based absorbents. First, the starting material is very inexpensive. Second, it is plentifully available and, once used and disposed of, the cellulosic component readily degrades, reducing the disposal problems inherent in the use of clay-based absorbents. Some particularly desirable methods of making cellulosic granules from paper waste are described in U.S. Pat. Nos. 4,560,527; 4,619,862; 4,621,011; and 4,721,059, which are incorporated herein by reference.
Although untreated cellulosic granules may form friable clumps, until the advent of the present invention, no practical method for making reliable and efficient clumping cellulosic absorbents was known. In the present invention, highly coherent clumps of cellulosic material are quickly formed when wetted by animal urine. Furthermore, the coherent clumps are easily maintained until removed. The present invention thus constitutes an important contribution to the animal litter art.